cmd/update-report: fix to show new tag

[hyuraku]

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fix cmd/update-report to show new correct tag. When I executed brew update, new_tag was backup/remove-popen-read-20-00-21, but I expected it was 2.7.1.

git -C /usr/local/Homebrew tag --list --sort=-version:refname "*.*"

 $ git -C /usr/local/Homebrew tag --list --sort=-version:refname "*.*"
2.7.1
2.7.0
2.6.2
2.6.1
2.6.0
2.5.12
--< omit >--

git -C /usr/local/Homebrew tag --list --sort=-version:refname

$ git -C /usr/local/Homebrew tag --list --sort=-version:refname
backup/remove-popen-read-20-00-21
backup/remove-popen-read-19-56-50
backup/gpg-verification-01-53-16
backup/days-19-30-23
backup/days-03-02-59
backup/days-03-02-52
backup/create-cache-00-29-47
backup/brew-cask-style-14-54-55
backup/activesupport-23-38-09
2.7.1
2.7.0
--< omit >--

[Rylan12]

Thanks, @hyuraku!